1. N. Kraus, Communication Sciences and Disorders, Northwestern University; and Departments of Neurobiology and Physiology, and Otolaryngology, Northwestern University, Evanston, IL 60208, USA.
2. T. J. McGee, S. G. Zecker, T. G. Nicol, D. B. Koch, Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA.
3. T. D. Carrell, Special Education and Communication Disorders, University of Nebraska, Lincoln, NE 68583, USA.